Turbo Boost, from my understanding and seeing it in action on other macs, is not application related, and is a function controlled and regulated by the CPU.
Compared to a MacBook Pro and a Mac Mini, with an i5 and i7 cpu, it's easy to determine when the cpu's go into TB mode, and on the i7 it's very easy to see when the CPU thermo-throttles to keep the CPU from getting too hot.
The first reply is intriguing, as it may simply be the case, however there is a thread somewhere (I'll update here when I find it again) where a poster shows the Turbo Boost behaviour of his 6 Core Xeon in his nMacPro, and according to the log file generated by Intel Power Gadget, the clock frequency is clearly seen to go over the nominal CPU base frequency. However, in my case, no matter what I throw at it, 3.7ghz is the absolute roof, even when consulting the log files.
Both MacBook Pro and MacMini are virtually always in TB boost frequencies when the computer isn't idle... and doing even light tasks, the monitor will spike into the TB frequencies. The only time the clock speed is forcefully kept at the nominal base frequency is when the CPU hits 100ºC... this is doesn't happen with the i5 MacBook Pro, as it always stays bellow 100ºC, but with the i7 Mac Mini, it takes around 5 minutes until it thermo-throttles.
What I find odd is that my 4 core Xeon shows no sign of TB.
[UPDATE]
Link to the Turbo Boost thread for nMPro 6 core.
http://forums.macrumors.com/threads/nmp-turbo-boost.1694931/
